I think you answered your question with your own observation of your birds. Any animal, espeically those with a herd/flock type social structure will be adversely affected to some extent when separated. For all the reasons you mentioned why you have them then that will be one of the trade-offs you'll have to make. As per your own observation, should you find two bachelors that can live peacefully together then they would both (you all) would be better served by it. In many instances, Roosters are just going to have a difficult disposition. They will be angry if you mess with their hens. They'll be angry if you take them away from their hens. They will be angry if they are penned with another roo, etc. As many (read all) dominant males in nature, they will be at their "best" when allowed to exist in as natural an environment as can be accommodated. As happens with horses, cattle, goats, etc , when it is a controlled breeding program the males are going to have aggressive issues that have to be dealt with. Those that don't will be the exceptions.